Nautilus

Nautiluses are members of the cephalopod family.  They have survived several severe extinction events that destroyed most other sea life.  A possible reason for the longevity of the nautilus clan is an ability to enter a type of "hibernation" life mode that can bridge long periods of poor environmental conditions.  Nautiluses are often confused with Ammonites- but look closely and you'll notice the patterns on the insides and outsides are actually very different.